which one is better in speed and everything?

your comparing a small sports car which is the 350z to a 4 door sporty family car, duhh the 350z is faster when it comes to speed, handling, cornering etc...

These are very different cars.
One is a Sportscar and one is a Sports sedan.
The NIssan 350z is definately faster because it is lighter and more powerful and more aerodynamic. But the interior scratches easily. It is hard to drive in manual. It has poor rear window visibility. It has bad practicialty with a tiny trunk and only 2 seats.
I have driven both cars.
The Acura has a much smoother and quieter ride. The Acura has better gas mileage. The Acura is much more reliable. The Acura is cheaper to fix and insure. The Acura is safer. The Acura is luxurious and comes with more features. The Acura has a better quality interior. The Acura has more seats and a much larger trunk.

that's comparing apples to oranges - not the same type of car... the Z is a pure sports car... great handling firm ride no real space except for 4 butt cheeks. The TL is a sedan... front wheel drive vs. rear wheel drive, four doors and a sporting sedan. The Z is going to be faster but the TL is going to be more comfortable and have more space. You need to look at your current needs ... if you can do without the space and dont have to drive in adverse weather but so much, the Z is a great car. Otherwise...

These 2 cars are not comparable. The 350Z is a 2-seater, and will blow the doors off the Acura. The Acura has a rear seat. If you want a comparable Honda to the Z-car, it's the S2000. The Nissan 350Z, however, has much more torque than the Honda and in a flat-out drag race, the Nissan will humiliate the Honda as well. Nissan motors are much more powerful than Honda motors, and are more reliable than Honda motors are.